Just wanted to post that I was able to get OpenBSD 4.0 working on my ESX 3.0.1 server. Others have posted information regarding OpenBSD on VMWare Server, but nobody had actually said whether or not it would work on ESX.

If you install the vmware tools per the directions below, Virtual Infrastructure Client will show the VMWare Tools with a status of OK, and you will be able to shutdown or restart the OS from the Virtual Infrastructure Client without having to login to OpenBSD.

VMWare doesn't support OpenBSD as a VM operating system. Under VMWare Server, people have gotten it to work by choosing FreeBSD as the "Guest Operating System." For some reason, ESX does not support FreeBSD like VMWare Server does.

Unfortunately the most complicated thing about this procedure is that ESX does not appear to come with a copy of the FreeBSD vmware tools. On VMWare Server, you can choose "Install VMWare Tools" from the vmware client window, mount /dev/cd0a /mnt, and see the vmware-freebsd-tools.tar.gz file. As far as I could tell, this file was not available under ESX. Therefore, to get the file, I had to download a copy of VMWare Server, do an install of OpenBSD and use the procedure above to get a copy of the file. If anyone from VMWare is listening, it would be great if you would provide a direct download for this file for your valuable ESX customers!

*Note that you can use the command line to provide the parameters for the shutdown command instead of compiling a new version of shutdown (which was recommended elsewhere).

10. If you want your VM to sync time with the ESX server on shutdown, you can shut down the VM and edit the .vmx file:
tools.syncTime="TRUE"
*Since those of us on ESX never shutdown our OpenBSD boxes (all hail vmotion!), a better option is just to enable ntp.

11. Restart the OpenBSD VM. If everything is working properly, on the VM Summary page, the tools should show as OK. You should also be able to choose "Shutdown Guest" or "Restart Guest" from the VI Client.

FYI, I also did some minimal testing with the default "Flexible" network adapter. I was able to get 13 Megabyte/sec transfer rate using FTP, which is fine for my limited usage. I understand that OpenBSD now includes a vmxnet driver, but I have no idea how to enable it on the ESX side. Whenever I edit the .vmx file to change the Ethernet0.virtualDev from "vlance" to "vmxnet", ESX simply overwrites my setting when the server starts up. If anyone has any suggestions for this, I'd be happy to hear it.

Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (main) pending.
Starting program: /emul/freebsd/sbin/vmtoolsd
Program terminated with signal SIGABRT, Aborted.
The program no longer exists.
You can't do that without a process to debug.

Yes unfortunitly there is no port of VMTools for OpenBSD, i have tried the FreeBSD emulation mode with all the other crap many times with no real success either.

I run my virutal machine raw, it seems to perform quite well, if i do run a gui it seems to chop a bit (no copy paste or clipboard or anything) but KDE runs quite well, a lighter desktop manager like XFCE is almost unnoticable.

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Also you can enable hardware acceleration under (right click VM) Settings -> Display it helps a bit too, the VMWare Fusion 3d accleration is MUCH improved ...

If you really are looking for performance, create a INDEPENDENT disk and make sure to ALLOCATE DISK SPACE NOW, this helped mucho in performance (I also have a VM of OS 10.6.2 running, it was a REAL headache, using a modded boot cd to boot, but it's working great, all updates and everything)

__________________
The more you learn, the more you realize how little you know ....

Yes unfortunitly there is no port of VMTools for OpenBSD, i have tried the FreeBSD emulation mode with all the other crap many times with no real success either.

I run my virutal machine raw, it seems to perform quite well, if i do run a gui it seems to chop a bit (no copy paste or clipboard or anything) but KDE runs quite well, a lighter desktop manager like XFCE is almost unnoticable.

@There0
thanks for the dmesg,it seem all the same on all VM platform(vbox,vmware,qemu),all return with the same 'unknown' devices error,my finding is the vmwaretools would be usefull for the ESX or ESXI version,which they depend heavily the OS detection by vmwaretools,well iam still trying right now on ESX trial ,so my observation so far,these vmwaretools only use-full for vsphere(ESX/ESXI) users,while vmware workstation/qemu/vbox just leave out it as it is "unknwon" .(will report back after finishing test on esx).

so 3d acceleration is not only for xp directx 9.0c emulation?would be work for *nix?anything noticeable?.Ah hackintosh?hehhe did you need to modified the bios to modified the acpi?yup man about the tweaking "ALLOCATE DISK SPACE NOW" i was already did it,really makes different.

btw are you Theo de Raadt??if yes,respect to you man!!!you giving me hope to the future of humanity

so 3d acceleration is not only for xp directx 9.0c emulation?would be work for *nix?anything noticeable?.Ah hackintosh?hehhe did you need to modified the bios to modified the acpi?yup man about the tweaking "ALLOCATE DISK SPACE NOW" i was already did it,really makes different.

I have tried enabling 3d acceleration only for Windoz and my MacOS virtual machines, both did make a difference, (notes below on MacOS VM) Linux's i only use BackTrack livedvd, (sometimes i test iso's in VM but don't have any one i use daily). I do not use GUI's on my OpenBSD installs (most are servers), the install of OpenBSD on my laptop is on raw metal, although i can boot it from VMWare through Windoz if i need (i do have 3D enabled, not sure how much it helps in this instance though).

NOTES ON MACOS;
This setup was a bit cranky, it actually took me about 2 months for find a proper solution. The VM was actually created in Fusion 3.0 as an "experiamental" 64bit SERVER (VM for Windoz does not have that type of VM yet) and then i used the config file (.vmx) to create a Windoz VM. This included use a precreated .iso file to actually boot the VM(no BIOS mods required) similar to BOOT132 and other others. There are VMTools available for the MacOS install as well (from Fusion 3) and it's QUITE SMOOTH (especially with dedicated disk space).

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The more you learn, the more you realize how little you know ....